short multi-scale bass questions

[Alex Shroyer]

I do not own a bass guitar so to rectify that problem my 2nd build will be a 4-string bass, but with a short scale length for comfort and portability.

Here are some fretboard dimensions to start with link.

Any suggestions for fretboard overhang? I have no intuition how much a bass should have.

[Jarno Verhoeven]

I would say tapering from 30 to 30.5" does not get you enough of an advantage to warrant the extra faff of tapering frets. Keep them straight, that will even allow you to buy a pre-slotted board (and remove a few frets on the top).
What kind of neck construction are you going to use?

[Alex Shroyer]

I'm slotting the board myself so it's really not much extra trouble to do a multiscale. Instead of "measure twice, cut once" it's just "measure four times, cut once". Neck wood will either be maple or pine, fretboard will be oak. Bolt-on, with an adjustable truss rod.

How far apart would you say the two scale lengths should be to make it worthwhile? 30" and 31"?